Current conventional synthetic diamond used in granite cutting, concrete cutting, and polishing applications is typically 40/50 and 50/60 mesh grits. These synthetic diamonds are typically smaller in size than the industry demand and are also irregular in shape. In terms of product quality, the thermal strength is not high enough for the above applications as they are randomly grown from HPHT synthesis from graphite in the presence of metal solvent catalyst. On the other hand, the thermal strength of natural diamond is sufficiently high for such applications; however natural diamond is too strong and brittle such that natural diamond is not self-sharpened through micro-chipping. Rather, natural diamond itself is polished, dulled, and tends to macrofracture instead of cutting the workpiece material. Therefore, a control of both grit sizes and individual grit property (e.g. thermal strength) during the HPHT process is not currently readily available in an industrial diamond industry where larger grits are desirable, e.g., 20/30 and 30/40 mesh over the standard 40/50 and 60/70 mesh grits in saw diamond blade and core drill bit manufacturing industries. Natural diamond is generally available in competition with synthetic diamond materials, although the supply of larger natural diamonds is limited and makes their use economically impractical.
Introduction of synthetic diamond has revolutionized the construction industry over the past four decades with the diamond saws for cutting and grinding stone, concrete, marble, and other hard materials. However, there is a new industry that is currently growing and involves the grinding and polishing of gravel aggregated concrete. This industry is in need of improved diamond tool performances over the conventional saw segment type products made with conventional synthetic diamond or natural diamond. Improvements such as self-cutting/self-sharpening, reduced dull-cutting action, and larger size grits (e.g. 10/20 to 20/30 mesh) over conventional size grits (30/50 mesh) would be a significant contribution to the industry.
Currently available grit suppliers of both natural and synthetic diamond are generally limited in their ability to provide large quantities despite some recent improvements in performance. Even synthetic diamond producers cannot currently handle large quantity (like 20 million carats per year) for the grit sizes of 10/20, 20/30, 30/40 mesh within a viable price range.
A number of efforts have been made in an attempt to provide improved abrasive grits with some degree of success. For example, thermally stable PCD (TSP) has been crushed to obtain fragmented grits. These fragmented grits can be sorted and debris removed to provide a TSP grit. However, these TSP grits are random in shape and tend to have highly irregular surface contours. Further, much of the product is lost during crushing as debris. Further, the step of crushing ultrahard TSP material is itself a very difficult and expensive process.
Although somewhat successful, efforts to provide commercially useful synthetic grits suffer from a variety of shortcomings that limit their potential use, including materials limitations, cost effectiveness, product quality limits, and process efficiency limitations, among others. As such, abrasive materials capable of use in the gravel aggregate and related industries having larger grit sizes, increased thermal stability, and cost effectiveness, continue to be sought through ongoing research and development efforts.